Covid 19 coronavirus: No signs of virus in wastewater testing, but people urged to remain vigilant

Wastewater testing by ESR has found no signs of community spread of Covid-19 but the crown research institute is still urging people to stay vigilant.

Testing around the area of the latest cases had not picked up signs of the virus, the institute said.

Two cases of Covid-19 were identified in Auckland this week after another was picked up a few days earlier in Northland.

Samples from Whangārei collected on January 26 and samples from the North Shore, Western Auckland, Central Auckland, Hamilton, Rotorua and Christchurch collected on January 25 for testing have all come back negative.

Dr Brent Gilpin says the results are pleasing but should not dissuade people from going for tests.

"Highly infectious individuals can shed billions of viruses, which means it is possible to detect in wastewater the presence of just a few infected individuals, but testing can't exclude the possibility of one or two infectious individuals," he said.

A wastewater treatment plant viewed from Māngere Mountain. Photo / Alex Robertson

"It's an extra layer of protection to add to the existing methods New Zealand already has in place.

"Anyone who is symptomatic or thinks they may have been exposed to an infected person must get tested regardless of the sewage testing results."

Gilpin said the institute continued to collect and analyse sewage samples from other locations throughout the country.

It will report to the Ministry of Health any unexpected positive detections.

Earlier in January, testing of Christchurch wastewater at the same time as there were a number of cases in managed isolation facilities, and sewage from the Jet Park Hotel, returned consistently positive results.

The wastewater surveillance research project is funded by Ministry of Business, Innovation and Employment.